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  <div class="section" id="encrypt-class">
<h1>Encrypt Class<a class="headerlink" href="#encrypt-class" title="Permalink to this headline">¶</a></h1>
<p>The Encrypt Class provides two-way data encryption. It encrypted using
the Mcrypt PHP extension, which is required for the Encrypt Class to run.</p>
<div class="admonition important">
<p class="first admonition-title">Important</p>
<p class="last">This library has been DEPRECATED and is only kept for
backwards compatibility. Please use the new <a class="reference internal" href="encryption.html"><em>Encryption Library</em></a>.</p>
</div>
<div class="contents local topic" id="contents">
<ul class="simple">
<li><a class="reference internal" href="#using-the-encrypt-library" id="id1">Using the Encrypt Library</a><ul>
<li><a class="reference internal" href="#setting-your-key" id="id2">Setting your Key</a></li>
<li><a class="reference internal" href="#message-length" id="id3">Message Length</a></li>
<li><a class="reference internal" href="#initializing-the-class" id="id4">Initializing the Class</a></li>
</ul>
</li>
<li><a class="reference internal" href="#class-reference" id="id5">Class Reference</a></li>
</ul>
</div>
<div class="custom-index container"></div><div class="section" id="using-the-encrypt-library">
<h2><a class="toc-backref" href="#id1">Using the Encrypt Library</a><a class="headerlink" href="#using-the-encrypt-library" title="Permalink to this headline">¶</a></h2>
<div class="section" id="setting-your-key">
<h3><a class="toc-backref" href="#id2">Setting your Key</a><a class="headerlink" href="#setting-your-key" title="Permalink to this headline">¶</a></h3>
<p>A <em>key</em> is a piece of information that controls the cryptographic
process and permits an encrypted string to be decoded. In fact, the key
you chose will provide the <strong>only</strong> means to decode data that was
encrypted with that key, so not only must you choose the key carefully,
you must never change it if you intend use it for persistent data.</p>
<p>It goes without saying that you should guard your key carefully. Should
someone gain access to your key, the data will be easily decoded. If
your server is not totally under your control it&#8217;s impossible to ensure
key security so you may want to think carefully before using it for
anything that requires high security, like storing credit card numbers.</p>
<p>To take maximum advantage of the encryption algorithm, your key should
be 32 characters in length (256 bits). The key should be as random a
string as you can concoct, with numbers and uppercase and lowercase
letters. Your key should <strong>not</strong> be a simple text string. In order to be
cryptographically secure it needs to be as random as possible.</p>
<p>Your key can be either stored in your <strong>application/config/config.php</strong>, or
you can design your own storage mechanism and pass the key dynamically
when encoding/decoding.</p>
<p>To save your key to your <strong>application/config/config.php</strong>, open the file
and set:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nv">$config</span><span class="p">[</span><span class="s1">&#39;encryption_key&#39;</span><span class="p">]</span> <span class="o">=</span> <span class="s2">&quot;YOUR KEY&quot;</span><span class="p">;</span>
</pre></div>
</div>
</div>
<div class="section" id="message-length">
<h3><a class="toc-backref" href="#id3">Message Length</a><a class="headerlink" href="#message-length" title="Permalink to this headline">¶</a></h3>
<p>It&#8217;s important for you to know that the encoded messages the encryption
function generates will be approximately 2.6 times longer than the
original message. For example, if you encrypt the string &#8220;my super
secret data&#8221;, which is 21 characters in length, you&#8217;ll end up with an
encoded string that is roughly 55 characters (we say &#8220;roughly&#8221; because
the encoded string length increments in 64 bit clusters, so it&#8217;s not
exactly linear). Keep this information in mind when selecting your data
storage mechanism. Cookies, for example, can only hold 4K of
information.</p>
</div>
<div class="section" id="initializing-the-class">
<h3><a class="toc-backref" href="#id4">Initializing the Class</a><a class="headerlink" href="#initializing-the-class" title="Permalink to this headline">¶</a></h3>
<p>Like most other classes in CodeIgniter, the Encrypt class is
initialized in your controller using the <tt class="docutils literal"><span class="pre">$this-&gt;load-&gt;library()</span></tt>
method:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nv">$this</span><span class="o">-&gt;</span><span class="na">load</span><span class="o">-&gt;</span><span class="na">library</span><span class="p">(</span><span class="s1">&#39;encrypt&#39;</span><span class="p">);</span>
</pre></div>
</div>
<p>Once loaded, the Encrypt library object will be available using:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nv">$this</span><span class="o">-&gt;</span><span class="na">encrypt</span>
</pre></div>
</div>
</div>
</div>
<div class="section" id="class-reference">
<h2><a class="toc-backref" href="#id5">Class Reference</a><a class="headerlink" href="#class-reference" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="CI_Encrypt">
<em class="property">class </em><tt class="descname">CI_Encrypt</tt><a class="headerlink" href="#CI_Encrypt" title="Permalink to this definition">¶</a></dt>
<dd><dl class="method">
<dt id="CI_Encrypt::encode">
<tt class="descname">encode</tt><big>(</big><em>$string</em><span class="optional">[</span>, <em>$key = ''</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#CI_Encrypt::encode" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$string</strong> (<em>string</em>) &#8211; Data to encrypt</li>
<li><strong>$key</strong> (<em>string</em>) &#8211; Encryption key</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Encrypted string</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>Performs the data encryption and returns it as a string. Example:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nv">$msg</span> <span class="o">=</span> <span class="s1">&#39;My secret message&#39;</span><span class="p">;</span>

<span class="nv">$encrypted_string</span> <span class="o">=</span> <span class="nv">$this</span><span class="o">-&gt;</span><span class="na">encrypt</span><span class="o">-&gt;</span><span class="na">encode</span><span class="p">(</span><span class="nv">$msg</span><span class="p">);</span>
</pre></div>
</div>
<p>You can optionally pass your encryption key via the second parameter if
you don&#8217;t want to use the one in your config file:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nv">$msg</span> <span class="o">=</span> <span class="s1">&#39;My secret message&#39;</span><span class="p">;</span>
<span class="nv">$key</span> <span class="o">=</span> <span class="s1">&#39;super-secret-key&#39;</span><span class="p">;</span>

<span class="nv">$encrypted_string</span> <span class="o">=</span> <span class="nv">$this</span><span class="o">-&gt;</span><span class="na">encrypt</span><span class="o">-&gt;</span><span class="na">encode</span><span class="p">(</span><span class="nv">$msg</span><span class="p">,</span> <span class="nv">$key</span><span class="p">);</span>
</pre></div>
</div>
</dd></dl>

<dl class="method">
<dt id="CI_Encrypt::decode">
<tt class="descname">decode</tt><big>(</big><em>$string</em><span class="optional">[</span>, <em>$key = ''</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#CI_Encrypt::decode" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$string</strong> (<em>string</em>) &#8211; String to decrypt</li>
<li><strong>$key</strong> (<em>string</em>) &#8211; Encryption key</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Plain-text string</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>Decrypts an encoded string. Example:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nv">$encrypted_string</span> <span class="o">=</span> <span class="s1">&#39;APANtByIGI1BpVXZTJgcsAG8GZl8pdwwa84&#39;</span><span class="p">;</span>

<span class="nv">$plaintext_string</span> <span class="o">=</span> <span class="nv">$this</span><span class="o">-&gt;</span><span class="na">encrypt</span><span class="o">-&gt;</span><span class="na">decode</span><span class="p">(</span><span class="nv">$encrypted_string</span><span class="p">);</span>
</pre></div>
</div>
<p>You can optionally pass your encryption key via the second parameter if
you don&#8217;t want to use the one in your config file:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nv">$msg</span> <span class="o">=</span> <span class="s1">&#39;My secret message&#39;</span><span class="p">;</span>
<span class="nv">$key</span> <span class="o">=</span> <span class="s1">&#39;super-secret-key&#39;</span><span class="p">;</span>

<span class="nv">$encrypted_string</span> <span class="o">=</span> <span class="nv">$this</span><span class="o">-&gt;</span><span class="na">encrypt</span><span class="o">-&gt;</span><span class="na">decode</span><span class="p">(</span><span class="nv">$msg</span><span class="p">,</span> <span class="nv">$key</span><span class="p">);</span>
</pre></div>
</div>
</dd></dl>

<dl class="method">
<dt id="CI_Encrypt::set_cipher">
<tt class="descname">set_cipher</tt><big>(</big><em>$cipher</em><big>)</big><a class="headerlink" href="#CI_Encrypt::set_cipher" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$cipher</strong> (<em>int</em>) &#8211; Valid PHP MCrypt cypher constant</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">CI_Encrypt instance (method chaining)</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">CI_Encrypt</p>
</td>
</tr>
</tbody>
</table>
<p>Permits you to set an Mcrypt cipher. By default it uses
<tt class="docutils literal"><span class="pre">MCRYPT_RIJNDAEL_256</span></tt>. Example:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nv">$this</span><span class="o">-&gt;</span><span class="na">encrypt</span><span class="o">-&gt;</span><span class="na">set_cipher</span><span class="p">(</span><span class="nx">MCRYPT_BLOWFISH</span><span class="p">);</span>
</pre></div>
</div>
<p>Please visit php.net for a list of <a class="reference external" href="http://php.net/mcrypt">available ciphers</a>.</p>
<p>If you&#8217;d like to manually test whether your server supports MCrypt you
can use:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="k">echo</span> <span class="nb">extension_loaded</span><span class="p">(</span><span class="s1">&#39;mcrypt&#39;</span><span class="p">)</span> <span class="o">?</span> <span class="s1">&#39;Yup&#39;</span> <span class="o">:</span> <span class="s1">&#39;Nope&#39;</span><span class="p">;</span>
</pre></div>
</div>
</dd></dl>

<dl class="method">
<dt id="CI_Encrypt::set_mode">
<tt class="descname">set_mode</tt><big>(</big><em>$mode</em><big>)</big><a class="headerlink" href="#CI_Encrypt::set_mode" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$mode</strong> (<em>int</em>) &#8211; Valid PHP MCrypt mode constant</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">CI_Encrypt instance (method chaining)</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">CI_Encrypt</p>
</td>
</tr>
</tbody>
</table>
<p>Permits you to set an Mcrypt mode. By default it uses <strong>MCRYPT_MODE_CBC</strong>.
Example:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nv">$this</span><span class="o">-&gt;</span><span class="na">encrypt</span><span class="o">-&gt;</span><span class="na">set_mode</span><span class="p">(</span><span class="nx">MCRYPT_MODE_CFB</span><span class="p">);</span>
</pre></div>
</div>
<p>Please visit php.net for a list of <a class="reference external" href="http://php.net/mcrypt">available modes</a>.</p>
</dd></dl>

<dl class="method">
<dt id="CI_Encrypt::encode_from_legacy">
<tt class="descname">encode_from_legacy</tt><big>(</big><em>$string</em><span class="optional">[</span>, <em>$legacy_mode = MCRYPT_MODE_ECB</em><span class="optional">[</span>, <em>$key = ''</em><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#CI_Encrypt::encode_from_legacy" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$string</strong> (<em>string</em>) &#8211; String to encrypt</li>
<li><strong>$legacy_mode</strong> (<em>int</em>) &#8211; Valid PHP MCrypt cipher constant</li>
<li><strong>$key</strong> (<em>string</em>) &#8211; Encryption key</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Newly encrypted string</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>Enables you to re-encode data that was originally encrypted with
CodeIgniter 1.x to be compatible with the Encrypt library in
CodeIgniter 2.x. It is only necessary to use this method if you have
encrypted data stored permanently such as in a file or database and are
on a server that supports Mcrypt. &#8220;Light&#8221; use encryption such as
encrypted session data or transitory encrypted flashdata require no
intervention on your part. However, existing encrypted Sessions will be
destroyed since data encrypted prior to 2.x will not be decoded.</p>
<div class="admonition important">
<p class="first admonition-title">Important</p>
<p class="last"><strong>Why only a method to re-encode the data instead of maintaining legacy
methods for both encoding and decoding?</strong> The algorithms in the
Encrypt library have improved in CodeIgniter 2.x both for performance
and security, and we do not wish to encourage continued use of the older
methods. You can of course extend the Encryption library if you wish and
replace the new methods with the old and retain seamless compatibility
with CodeIgniter 1.x encrypted data, but this a decision that a
developer should make cautiously and deliberately, if at all.</p>
</div>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nv">$new_data</span> <span class="o">=</span> <span class="nv">$this</span><span class="o">-&gt;</span><span class="na">encrypt</span><span class="o">-&gt;</span><span class="na">encode_from_legacy</span><span class="p">(</span><span class="nv">$old_encrypted_string</span><span class="p">);</span>
</pre></div>
</div>
<table border="1" class="docutils">
<colgroup>
<col width="20%" />
<col width="14%" />
<col width="66%" />
</colgroup>
<thead valign="bottom">
<tr class="row-odd"><th class="head">Parameter</th>
<th class="head">Default</th>
<th class="head">Description</th>
</tr>
</thead>
<tbody valign="top">
<tr class="row-even"><td><strong>$orig_data</strong></td>
<td>n/a</td>
<td>The original encrypted data from CodeIgniter 1.x&#8217;s Encryption library</td>
</tr>
<tr class="row-odd"><td><strong>$legacy_mode</strong></td>
<td>MCRYPT_MODE_ECB</td>
<td>The Mcrypt mode that was used to generate the original encrypted data.
CodeIgniter 1.x&#8217;s default was MCRYPT_MODE_ECB, and it will assume that
to be the case unless overridden by this parameter.</td>
</tr>
<tr class="row-even"><td><strong>$key</strong></td>
<td>n/a</td>
<td>The encryption key. This it typically specified in your config file as
outlined above.</td>
</tr>
</tbody>
</table>
</dd></dl>

</dd></dl>

</div>
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